Exhibit 5.1

  ATTORNEYS AT LAW 777 EAST WISCONSIN AVENUE MILWAUKEE, WI 53202-5306 414.271.2400 TEL 414.297.4900 FAX foley.com

May 3, 2024

Plexus Corp.

One Plexus Way

Neenah, WI 54957

Ladies and Gentlemen:

We have acted as counsel for Plexus Corp., a Wisconsin corporation (the “Company”), in connection with the preparation of a Registration Statement on Form S-8 (the “Registration Statement”) to be filed by the Company with the Securities and Exchange Commission under the Securities Act of 1933, as amended (the “Securities Act”), relating to 870,835 shares of the Company’s Common Stock, $.01 par value (the “Common Stock”), that may be issued pursuant to the Plexus Corp. 2024 Omnibus Incentive Plan (the “Plan”).

As such counsel, we have examined: (i) the Plan; (ii) the Registration Statement, including the exhibits filed therewith or incorporated by reference constituting a part of the Registration Statement; (iii) the Restated Articles of Incorporation of the Company, as amended to date; (iv) the Amended and Restated By-Laws of the Company, as amended to date; (v) resolutions of the Company’s Board of Directors relating to the Plan and the issuance of securities thereunder; and (vi) such other documents and records and certificates of government officials as we have deemed necessary to enable us to render this opinion.

Based upon the foregoing, we are of the opinion that the shares Common Stock, when issued by the Company pursuant to the terms and conditions of the Plan and as contemplated by the Registration Statement, will be validly issued, fully paid and nonassessable.

We consent to the use of this opinion as an exhibit to the Registration Statement. In giving our consent, we do not admit that we are “experts” within the meaning of Section 11 of the Securities Act or within the category of persons whose consent is required by Section 7 of the Securities Act.

Very truly yours,

/s/ FOLEY & LARDNER LLP

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